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135 lines
8.2 KiB
Markdown
135 lines
8.2 KiB
Markdown
# Tesseract OCR
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[](https://ci.appveyor.com/project/zdenop/tesseract/)
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[](https://github.com/tesseract-ocr/tesseract/actions/workflows/sw.yml)\
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[](https://scan.coverity.com/projects/tesseract-ocr)
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[](https://github.com/tesseract-ocr/tesseract/security/code-scanning)
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[](https://bugs.chromium.org/p/oss-fuzz/issues/list?sort=-opened&can=2&q=proj:tesseract-ocr)
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\
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[](https://raw.githubusercontent.com/tesseract-ocr/tesseract/main/LICENSE)
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[](https://github.com/tesseract-ocr/tesseract/releases/)
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## Table of Contents
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* [Tesseract OCR](#tesseract-ocr)
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* [About](#about)
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* [Brief history](#brief-history)
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* [Installing Tesseract](#installing-tesseract)
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* [Running Tesseract](#running-tesseract)
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* [For developers](#for-developers)
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* [Support](#support)
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* [License](#license)
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* [Dependencies](#dependencies)
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* [Latest Version of README](#latest-version-of-readme)
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## About
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This package contains an **OCR engine** - `libtesseract` and a **command line program** - `tesseract`.
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Tesseract 4 adds a new neural net (LSTM) based [OCR engine](https://en.wikipedia.org/wiki/Optical_character_recognition) which is focused on line recognition, but also still supports the legacy Tesseract OCR engine of Tesseract 3 which works by recognizing character patterns. Compatibility with Tesseract 3 is enabled by using the Legacy OCR Engine mode (--oem 0).
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It also needs [traineddata](https://tesseract-ocr.github.io/tessdoc/Data-Files.html) files which support the legacy engine, for example those from the [tessdata](https://github.com/tesseract-ocr/tessdata) repository.
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Stefan Weil is the current lead developer. Ray Smith was the lead developer until 2018. The maintainer is Zdenko Podobny. For a list of contributors see [AUTHORS](https://github.com/tesseract-ocr/tesseract/blob/main/AUTHORS)
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and GitHub's log of [contributors](https://github.com/tesseract-ocr/tesseract/graphs/contributors).
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Tesseract has **unicode (UTF-8) support**, and can **recognize [more than 100 languages](https://tesseract-ocr.github.io/tessdoc/Data-Files-in-different-versions.html)** "out of the box".
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Tesseract supports **[various image formats](https://tesseract-ocr.github.io/tessdoc/InputFormats)** including PNG, JPEG and TIFF.
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Tesseract supports **various output formats**: plain text, hOCR (HTML), PDF, invisible-text-only PDF, TSV and ALTO (the last one - since version 4.1.0).
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You should note that in many cases, in order to get better OCR results, you'll need to **[improve the quality](https://tesseract-ocr.github.io/tessdoc/ImproveQuality.html) of the image** you are giving Tesseract.
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This project **does not include a GUI application**. If you need one, please see the [3rdParty](https://tesseract-ocr.github.io/tessdoc/User-Projects-%E2%80%93-3rdParty.html) documentation.
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Tesseract **can be trained to recognize other languages**.
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See [Tesseract Training](https://tesseract-ocr.github.io/tessdoc/Training-Tesseract.html) for more information.
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## Brief history
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Tesseract was originally developed at Hewlett-Packard Laboratories Bristol UK and at Hewlett-Packard Co, Greeley Colorado USA between 1985 and 1994, with some more changes made in 1996 to port to Windows, and some C++izing in 1998. In 2005 Tesseract was open sourced by HP. From 2006 until November 2018 it was developed by Google.
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Major version 5 is the current stable version and started with release
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[5.0.0](https://github.com/tesseract-ocr/tesseract/releases/tag/5.0.0) on November 30, 2021. Newer minor versions and bugfix versions are available from
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[GitHub](https://github.com/tesseract-ocr/tesseract/releases/).
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Latest source code is available from [main branch on GitHub](https://github.com/tesseract-ocr/tesseract/tree/main).
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Open issues can be found in [issue tracker](https://github.com/tesseract-ocr/tesseract/issues),
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and [planning documentation](https://tesseract-ocr.github.io/tessdoc/Planning.html).
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See **[Release Notes](https://tesseract-ocr.github.io/tessdoc/ReleaseNotes.html)**
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and **[Change Log](https://github.com/tesseract-ocr/tesseract/blob/main/ChangeLog)** for more details of the releases.
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## Installing Tesseract
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You can either [Install Tesseract via pre-built binary package](https://tesseract-ocr.github.io/tessdoc/Installation.html)
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or [build it from source](https://tesseract-ocr.github.io/tessdoc/Compiling.html).
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A C++ compiler with good C++17 support is required for building Tesseract from source.
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## Running Tesseract
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Basic **[command line usage](https://tesseract-ocr.github.io/tessdoc/Command-Line-Usage.html)**:
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tesseract imagename outputbase [-l lang] [--oem ocrenginemode] [--psm pagesegmode] [configfiles...]
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For more information about the various command line options use `tesseract --help` or `man tesseract`.
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Examples can be found in the [documentation](https://tesseract-ocr.github.io/tessdoc/Command-Line-Usage.html#simplest-invocation-to-ocr-an-image).
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## For developers
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Developers can use `libtesseract` [C](https://github.com/tesseract-ocr/tesseract/blob/main/include/tesseract/capi.h) or
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[C++](https://github.com/tesseract-ocr/tesseract/blob/main/include/tesseract/baseapi.h) API to build their own application. If you need bindings to `libtesseract` for other programming languages, please see the
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[wrapper](https://tesseract-ocr.github.io/tessdoc/AddOns.html#tesseract-wrappers) section in the AddOns documentation.
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Documentation of Tesseract generated from source code by doxygen can be found on [tesseract-ocr.github.io](https://tesseract-ocr.github.io/).
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## Support
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Before you submit an issue, please review **[the guidelines for this repository](https://github.com/tesseract-ocr/tesseract/blob/main/CONTRIBUTING.md)**.
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For support, first read the [documentation](https://tesseract-ocr.github.io/tessdoc/),
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particularly the [FAQ](https://tesseract-ocr.github.io/tessdoc/FAQ.html) to see if your problem is addressed there.
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If not, search the [Tesseract user forum](https://groups.google.com/g/tesseract-ocr), the [Tesseract developer forum](https://groups.google.com/g/tesseract-dev) and [past issues](https://github.com/tesseract-ocr/tesseract/issues), and if you still can't find what you need, ask for support in the mailing-lists.
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Mailing-lists:
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* [tesseract-ocr](https://groups.google.com/g/tesseract-ocr) - For tesseract users.
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* [tesseract-dev](https://groups.google.com/g/tesseract-dev) - For tesseract developers.
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Please report an issue only for a **bug**, not for asking questions.
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## License
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The code in this repository is licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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**NOTE**: This software depends on other packages that may be licensed under different open source licenses.
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Tesseract uses [Leptonica library](http://leptonica.com/) which essentially
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uses a [BSD 2-clause license](http://leptonica.com/about-the-license.html).
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## Dependencies
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Tesseract uses [Leptonica library](https://github.com/DanBloomberg/leptonica)
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for opening input images (e.g. not documents like pdf).
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It is suggested to use leptonica with built-in support for [zlib](https://zlib.net),
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[png](https://sourceforge.net/projects/libpng) and
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[tiff](http://www.simplesystems.org/libtiff) (for multipage tiff).
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## Latest Version of README
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For the latest online version of the README.md see:
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<https://github.com/tesseract-ocr/tesseract/blob/main/README.md>
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